Firearms have long included sights mounted on the barrel for improving the accuracy and reliability of shooting. Generally the sight is a front sight—or peep sight—mounted adjacent the muzzle of the barrel of the firearm. In addition, a rear sight can be included that is mounted at the breech of the firearm. Aligning the object or target both horizontally and vertically within both the front and the rear sights, and keeping the object or target aligned therein, is a crucial factor in developing accurate shooting—marksmanship—skills. To further develop and enhance one's shooting skills, scopes of varying degrees of magnifying power can be mounted to the firearms, especially rifles—although it is now possible to mount scopes to certain types and calibers of handguns. However, situations may occur where it is not necessary to have both a mounted scope and a front or peep sight. Thus it would be desirable to be able to mount and a scope to the firearm for use when needed but capable of detachment from the firearm when not needed.